Scientists from the U.S. National Oceanic and Atmospheric Administration (NOAA) set up an experimental raft at the mouth of New York City's Bronx River last spring. Hanging beneath it were long, sock-like tendrils that had been seeded with Geukensia demissa, commonly known as ribbed mussels. The point of the two-year experiment was to see whether mussels would survive or even thrive given the industrial and organic effluent that flows from the Bronx into the greater New York Harbor. If the mussels did in fact prosper in this environment, it could have implications for how we might help clean up coastal waters in various parts of the world.

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The idea of using bivalves to purify waterways is not a newfound idea. In fact, businessmen and scientists are increasingly considering the mussel, both as a way to produce a commercial product and to explore their potential as water filterers.

Uppermost on the minds of the researchers out on the Bronx River — a joint project of NOAA and the Long Island Sound Study — was whether certain types of mussels could be used to rid coastal waters of an onerous influx of nitrogen generated from sewage, fertilizers, and other pollutants.

"In areas where water quality is degraded... from nutrient over-enrichment, the ribbed mussel looks like a dependable partner to help us recycle lost nutrients back into useful products," said Gary Wikfors, an aquaculture expert and chief of the biotechnology branch at NOAA's laboratory in Milford, Connecticut.

In macro-ecological terms, mussels and their bivalve kin are the intestines of coastal ecosystems. Their filters remove organic particulate matter from the water column, particularly phytoplankton. Oysters were long the bivalve of choice in the U.S., but the mussel has certain advantages that are being increasingly touted. Although an individual oyster can filter much more water — an estimated 20 to 30 gallons per day — mussels grow more densely than oysters.

Unfortunately, many of the oyster reefs that have been built in places like the Chesapeake Bay and Long Island Sound are gone and take a long time to reestablish. However, mussel rafts can be immediately established, working throughout the water column at incredible densities.

Clean water is something in short supply at the mouth of the Bronx River. But as Newell and the NOAA scientists started pulling up yards of rope from underneath the experimental mussel raft, it did seem plausible that mussel culture could one day get going in New York — if not to produce edible mussels, then to grow mussels that would lend a hand in cleaning the water.